Thermostat.



. mritnsTATEs PATENT ()FFICE.

enonenw. or PIQUA, 01-110, ASSIGNOR T w. It. xsvs, or PIQUA, OHIO.

THEBMOSTAT.

p p p Specification of Letters Patent. 1 atentedJune 16, 1914. pApplication flied August 26, 1912. Serial No, 7171164. j i H ,Toa lZ whom it may consent:

Be it known thatflI, Gnome Lemma,

a citizen of the .UnitedStates, and a resident of Piqua, oounty of Miami, and State of Ohio, havecinvented yanew and useful Improvement in Thermostats, of which the followingis a specification. i i

My invention relates to. thermostats for use in connection with-automatic fire alarm or fire extinguishing systems, Its, object, more particularly, isXto produce :such a thermostat as will be extremely sensitive to changes in temperature, constant with respect to its critical. point of operation, and readily adjustablelwith respect to the temperature at which it, will operate. Primarily it is designed to cause a change in electrical circuitsupon the risein tempera ture of the surroundingair to a certain predetermined point, it operating equally well to close a circuit upon such a; rise; intent perature or to openlone, or to close one-and 1 open another accordingto the ucharacter of :view of my the rmostat..v

- theelectrical apparatus with which it is associated. w l

A further object is to provide,inyconnection with the automatically operated part ofmy thermostat,such, testing means as will permit the manual closing orbpening, or closing and opening, ofjthecircuits in the same manner as if automaticallydtine, for

purposes of testing not only 3 the thermostat itself, but theassociated*circuits and pieces of apparatus. i

. Referring tothe accompanyingdrawing which forms a part of this specification, the single figure there shown is across-sectional Referring to. this figure, l isiabase of brass or other; suitable metal whichforms .the means of attachment for the thermostat, as a whole, to the wall, floor, ceiling or other support to which; it is :to be secured. Secured rigidlyqto this,basefpreferably by screw-threading the parts as shown, is a tube, which I refershall be of hard rubber,

although it mavbe ofany other suitable substancenot affected by moisture and having a relatively. high coefiicient of expansion with respect to'the ordinary metals. This tube :2, besides forming an; important mechanical link in the thermostat, also serves the purposeof a containing case for inclosing the moredelicate parts. Extending from the base liwithin the tube is a standard 3, preferably, though not necessarily integral with the base 1, this also being 0% metal, such as brass. This standardis provided at its extremity with an angularextension or bracket 4, bored with a cylindri cal hole 4. for a purpose to be described. Within'the standard at a point near its base is an insulating bushing 5 of hard rubber or similar material, the purpose of which is to carry the contact screw 6 in such manner as to'rigidly support this screw and to insulate it from the bracket. This screw is threaded into the metal collar in the bushing 5 so as to permit of its backward or forward'adjustment, as may be required. Theextension 4 of thestandardor bracket 3 carries a long flexible contact spring7, this spring being rigidly secured at its upper end to the'extensi'on 4 by one or more screws 8 or other equivalent means. The contact spring 7 carries a contact point 7 and the screw 6 asimilar contact 6, these two contacts being so disposed that when the spring is pressed to the left,.as viewed in the drawing, the contactswill engage, thus completing the electrical circuit from the wire 9 leading to the base '1 of the instrument, through the standard 3, extension 4, spring 7 contacts 7 and (3 contact screw 6 to theyotherleading in wire 10. fit a' 'point slightly below'the point of support of the spring 7 there is rigidly secured to this.

spring, by means of one or more screws equivalent means, a block or stirrup 12, pre ferably of brassor other metal. This block is provided on its upper face with a conical recess, as shown, for the reception of one of the points of a compression rod 13, also of brass or similar metal. The upper end of the tube 2 is closed by-ametal disk 14-, preferably screw-threaded into the end of the tube. Through the center of this closing disk 14 there passes the screw 15, thelower end of which is provided with a conical recess similar to that in the block 12. This screw 15 may be adjusted up or down, as may be" required, by means of its screwthreaded connection with the disk 14. The rod 13 is provided with a cone shaped point at eachend and issupported between the recesses inthe block12 and the screw 15, as clearly indicated. The hole 4: in the extension 4 of the bracket 3 is in alinement with spring 7 .amount'or" travel which will be" permitted .as those ofhthe contact screw 6 and its co normal position, as viewed inv the drawing. 15

. and in such relation that at normal temper.-

through and yetbe laterally "supported thereby to facilitate the assembly ofthe arts. o P For operation the screw 15 is turned down so as to exert suflicient pressure through the rod 13 on theblock 12 to cause that block to. move down from the normal position in which "the spring 7 tends to hold it This.

downward movement ofth'e block '12 isper mitted by the flexibility of that partof the spring 7 which lies bet'weenthe block 12'and thesupporting projection 41, and results in thespring 7 being ,flexed to the right of its The'screw 6vis so adjusted. that for normal temperatures its contact point 6 will not; be engaged by the contact point 7 on the The operation of the device-dependson the fact thathardrubber has, a much greater coeflicient of expansion than brass orother common metals. When, therefore, a rise in temperature takes place, the length of the hard rubber tub 2 will inereasemore rapidly than the length of the combined metal parts extending from h base l 'to the cap 1 1 within the-tube, and, as a result, thescrew 15 will have such-movement as to relieve the pressure exerted. bythe rod 13011 the block 12, which will allow this block to move upwardly, v,as shown in the drawing, and thus permit the spring 7 to assume more I nearly its norm'al'position. In doing this, the contact 7 will approachthe contact (3, ant. at a certain rise in temperature willaactually engage it, thus closing the circuit between the leading in wires Sand 10.1-Obviously,the amount whichspring '7 is-de-i flected fromits normal positionwill depend on the adjustment of the screw 15,-and. the

this spring beforeitactually closes cont-act will d; dszizt on the position of the screw 6. By the adjustmentwct' these two screws, therefore, the device. may bemade to close its circuit for any given temperature.

If desired, an additional standard 16, shown in dotted lines, may be provided if I the thermostat is to be required to open 'a determined temperature is reached. This standard 16 .maycarryy by meansof anilisulating bushing 17, another contact screw l8, 'also shown in dotted lines. 'Thisscrew may carry a contatflS, cooperating with a contact7- on the spring "(,t-he' construction ofthese parts being'in all respects the same operating parts, with the exoeptionthat the screw 18 and itscooperating contacts are placedon the. opposite side of the spring 7 atures there will be engagement between the 1 contacts 7 2 and 18 this engagement being in tr:

could be omitted. If, however, the thermostat were requiredto open: one circuit and close anothe'r,both the screws 6'- and '18 and broken 5 when the-spring the left when the critical temperature is reached.

cause for an ordinarveircuit closing thermostat these would i .:.it'be.mqu1red. If the required to hold a cirrruit closed ad to open it ripa iven rise .'-ture,-then the contact screw 6 their" associated parts" would be present.

Thexwire19 formsaleadingin: wire for the contact screw 18in t-hejsame'manner as the wire 10 doesffor the screwg 6.

I provide for greatsensitiveness of the device to-temperature changes byiso .prop'ortioning the: parts t-hatfa verysmall downward movement of the: block 12 wilt result in fagreatly' multiplied. movement :of the contact .end of-the spring 7,'this endbeing attained by making the distances from' the support-.4: to the block'12,and'rfromithe spring 7 tothe lower: pointpf-the rod13, relatively small with respect to thedistance from the'block 12 to thetcontact'end ofthe spring. Almost any .degree of sensitiveness can be attained by variationsi-nthe relative lengths of these lever arms. 7 p o.

' ln order that the device-may be readil available for-testing 'with'oi'itin any way at fecting the adjustmentof itsjparts, I pr0- "vide a-spring 20, securedlat one end to the innersideof the tube '2' by means of the screws or r1vetsf21. This spring is bent that its tree and will its-sent ent it the lower end of theslprirtgr. It carries, opposite'the lower end of the'spring 7', an insulating projection 22,fso---. d ispos ed that when the sprihgQO: is" p essed to-the lett, as viewed in the 'drawing it spring "to theleit withouti-inaking electrical contact therewith. I provide a push button 23, extending through- :the wallet the tube 2, so that *apressure of the fingeron thisbutton. will, throughtheyspring-QO, cause the spring 7 to niove so as to break its normally closed contacts 7 andnl8,.:if such there hey-or to close the normally open con- 'ta'etsti andlor 'to'o'penone pair andclose By jpressing the other, as the: case may :he.

vill :lserveqto press the this but-ton23, therefore, is' possible-not ouly to test "manually the contacts of the thermostatzitself, "but also to: test the operati on of whatever circuitsfor.v other} devices may-be associ ted therewith. I a

. Perhaps the simplest adaptation thermostat to useful purposesxis m that of an automatic I fire: alarm. system for buildlugs wherein an---'ord inary: alarm bell and battery maybe-placed in a circuit in series 9 and 10. leading from the in temperature'wil'l, by ants;- t and .7 1 cause I the i'll 1 l the. ufiwat. .11 closing the; con.

sounding of the alarm and at the same time the system may be tested by merely pressing upon the button 23. Of course, the device is equally adapted for the automatic circuit control of any of the well known fire alarm or fire extinguishing systems. I

An inspection of my devicewill'show that the relatively great expansion or contraction of the hard rubber tube, which forms a link betweenthe extremities of the device, causes a relative movement between the extension 4, rigidly secured to one end of the device,

and the lower end of the rod 13, connected with the other end of the device, Relative movement of these parts is rovidedfor by permitting 'the'rod 13 to side within the bracket 4. The spring 7 formsvirtually a;

circuit changing lever, and in order thatithe very small movement imparted to the power end of this lever by virtue of the slidingaction of the rod 13 within the bracket-4 may produce a relatively large movement of the working end of the lever, the ratio between the powerend andthe working end is made a large one.

Having thus described my invention, what I claim as new and desire to secure by United States Letters Patent is: 7 1. In a thermostat; atube of highly expansible material, a base and a cap for said tube, a contact spring-lever within said tube, one end of said sprmg-lever being rigidly fixed with respect to said base, a thrust rod having pointed ends, a stirrup attached to said spring-lever near its fixed end and engaging one end of said thrust rod, an adjustable bearing in said cap for engaging the other end of said thrust rod, and a stationary contact cooperating with the free end of said spring-lever for controlling an electrical circuit, substantially as described, a

2. In a thermostat; a tube of highly ex pansible material, a base and a cap for said tube, a contact spring-lever within said tube, one end ofsaid spring-lever being rigidly fixed with respect to said base, a

thrust rod having pointed ends, a stirrup attached to said spring-lever near its fixed end and engaging one end of said thrust rod, an

adjustable bearing in said cap for engaging the other end of said thrust rod, a statlonary contact cooperating with the freeend of said spring-lever'for controlling an electrical circu'it, and, a push button for manually oper- 

